indexes: abbreviations and other reference tools

References to material not contained within the body of the text, such as bibliographies, glossaries, illustrations and tables, require a locator in letters as well as in numbers. The numeral can be printed in boldface type, while the element in letters is presented in italics, usually as an abbreviation:

• 367 bibliogr.
  • Bibliography
• 54 (fig. 21)
  • Figure
• 345 glos.
  • Glossary
• 68 (fn. 2)
  • Footnote
• 54 ill.
  • Illustration
• 36 (hn.)
  • Headnote
• facing 60
  • plate

When more than one significant reference to an item is made on the same page of a text, and each piece of information is useful, the words bis (twice) and ter (three times) may follow the page number in the index:

• War of 1812–14, 78 (bis), 87 (ter)

In indexing works with many words on a page, make the reader’s search for information easier by assigning a letter or number to each part of the page. For example, in the Encyclopaedia Britannica, the letters a, b, c and d refer to the top, upper middle, lower middle and bottom of the left column of a page, and e, f, g and h to the same parts of the right column (23a, 23b, 23c, etc.).

Explain all abbreviations and special reference codes in an introductory note to the index.